This was sent on Saturday but didn't make it to the list (possibly a problem my end).
Incidentally, I've since restarted Dovecot to see if that helped. It didn't.
Luigi Rosa wrote on 01 August 2009 14:10
Frank Leonhardt said the following on 01/08/09 12:00:
I've searched as far as I can for any known problems using Outlook.
What about the size of the mailbox?
Each version of Outlook has its own issue regarding the maximum size of PST files.
Good guess knowing Outlook, and a good question as I'd forgot to mention it, but these are IMAP mailboxes, and they're therefore 'cached' in individual .pst files for each box. Originally I'd suspected it was a size issue with Dovecot as it worked when I split the files, but I now know that simply copying the files is enough. FWIW the problem mbox files are ~100M on the server - nothing exceptional.
Incidentally, having had much experience of Outlook, 2Gb is a good working assumption (32-bit signed addressing). This was the official limit in earlier versions (pre-Unicode), but if you reached it, big trouble. Personally I never let them get to more than 1.5Gb. Outlook 2003 is an interesting case - standard PST files are Unicode but those used for caching IMAP are ASCII, so you still have the limit to worry about. I believe the physical limit was removed in Outlook 2007 - the upper limit is now set in the registry at a default of ~20Gb - but creating bigger files is still bad news as you'll either wreck a Microsoft filing system somewhere or need to import the file into an older version of Outlook (or data recover tool).